import java.util.Scanner;

/**
 * @Author YuanYuan
 * @Date 2022/4/23
 * @Time 17:27
 */
public class TestDemo {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int num = scanner.nextInt();
        int flag = 1;
        for (int i = 2; i <= Math.sqrt(num); i++) {
            if(0 == num%i){
                flag = 0;
                break;
            }
        }
        if(1 == flag) {
            System.out.println("num "+num+" 是一个素数。");
        }else {
            System.out.println("num "+num+" 不是一个素数。");
        }
    }
}
